Banjo counter/height above toilet tank

I have a banjo counter with 32.5 inches clearance below the front edge. I am looking for a Toto ADA height toilet that will fit under here and have room to do potential repairs within the tank without removing either tank or the whole toilet. The Toto Ultramax is appealing, but at 29.25 inches to the top of the tank I'm not sure that there will be enough room. One would gain maybe 1.5 inches when the tank lid is off, for a total of 4.75 inches between counter bottom front and open tank top. My question is - just how many inches of clearance space is advisable? (I have replaced a flapper by feel with only about 3" clearance - also involved a mirror, flashlight and some arm contortions!).

I see that the Toto Supreme ADA is a similar style to the Ultramax and has a much lower profile (only 25.5 inches high), but the flushing system is one step below the Ultramax and that has me somewhat concerned.

Don't know about the ADA version, but apparently the Supreme flushes well enough that they make an ECO version that flushes 500 grams with 1.28 gallons in the regular elongated bowl. Typically the ADA height bowl flushes as well or better than the regular elongated.

A local dealer gave me a brochure (today) about the Toto Eco toilets. It appears that the Eco Supreme is not available in ADA height, unfortunately. The flushing mechanism on the Eco versions is something new, it seems, and I believe the description said that it was akin to the GMax as opposed to the Power Gravity so am not sure whether the Supreme and Eco Supreme can be compared in flushing. That being said, the dealer seemed to think that the Supreme ADA should fit ordinary residential needs.

Terry has the one-piece ADA Plymouth with Power Gravity listed at 675 grams. If you subtract the 2" ridge on the back of the tank lid, it's about the same height as the Supreme. Performance should be close.